A 32-year-old woman wakes with sharp pain in her right eye. Initially she felt as if she had a piece of glass in her eye. Now her eye feels sandy and dry but is slowly improving. She reports no history other than a remote corneal abrasion from a tree branch several years ago.

A 47-year-old white woman complains of 3 years of bilateral dry-eye symptoms. She specifically reports a constant sensation of dryness, burning, and sensitivity to light in both eyes. Preservative-free artificial tears do not relieve her symptoms.